Collagen/heparin sulfate scaffolds fabricated by a 3D bioprinter improved mechanical properties and neurological function after spinal cord injury in rats

Abstract

Effective treatments promoting axonal regeneration and functional recovery for spinal cord injury (SCI) are still in the early stages of development. Most approaches have been focused on providing supportive substrates for guiding neurons and overcoming the physical and chemical barriers to healing that arise after SCI. Although collagen has become a promising natural substrate with good compatibility, its low mechanical properties restrict its potential applications. The mechanical properties mainly rely on the composition and pore structure of scaffolds. For the composition of a scaffold, we used heparin sulfate to react with collagen by crosslinking. For the structure, we adopted a three-dimensional (3D) printing technology to fabricate a scaffold with a uniform pore distributions. We observed that the internal structure of the scaffold printed with a 3D bioprinter was regular and porous. We also found that both the compression modulus and strengths of the scaffold were significantly enhanced by the collagen/heparin sulfate composition compared to a collagen scaffold. Meanwhile, the collagen/heparin sulfate scaffold presented good biocompatibility when it was co-cultured with neural stem cells in vitro. We also demonstrated that heparin sulfate modification significantly improved bFGF immobilization and absorption to the collagen by examining the release kinetics of bFGF from scaffolds. Two months after implantating the scaffold into transection lesions in T10 of the spinal cord in rats, the collagen/heparin sulfate group demonstrated significant recovery of locomotor function and according to electrophysiological examinations. Parallel to functional recovery, collagen/heparin sulfate treatment further ameliorated the pathological process and markedly increased the number of neurofilament (NF) positive cells compared to collagen treatment alone. These data suggested that a collagen/heparin sulfate scaffold fabricated by a 3D bioprinter could enhance the mechanical properties of collagen and provide continuous guidance channels for axons, which would improve the neurological function after SCI. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1324-1332, 2017.

3D printing collagen/chitosan scaffold ameliorated axon regeneration and neurological recovery after spinal cord injury

“…Thus, the existing of traditional manufacturing technologies limited the application of engineering of biodegradable polymer implantations. In order to solve these problems, 3D printing appeared recently as a new technology that could meet the requirement of suitable shape, size, and surface morphology for spinal cord implantation . In this study, a 3D bioprinter was used to manufacture a collagen–chitosan scaffold according to the designed structure.…”

“…Compatibility of scaffolds was detected with thiazole blue (MTT) assay and scanning electron microscopy (SEM). After seeding NSCs on scaffolds for 3 days, MTT assay was performed as previously described . The absorbance at 490 nm was examined with an SS‐300 immunoanalyzer.…”

“…After seeding NSCs on scaffolds for 3 days, MTT assay was performed as previously described. 23 The absorbance at 490 nm was examined with an SS-300 immunoanalyzer.…”

“…Eight weeks after SCI, rats were anesthetized and electrophysiology examination was performed as previously described. 23 For motor-evoked potential (MEP) recording, the stimulating electrode was inserted into cortical motor area at the intersection of coronal suture and sagittal suture, and the recording electrode was inserted into the tibialis posterior nerve. Stimulus intensity was 46 V, the pulsewidth was 0.2 ms, and the stimulation frequency was 1 Hz.…”

5‐Nonyloxytryptamine oxalate–embedded collagen–laminin scaffolds augment functional recovery after spinal cord injury in mice

“…A scaffold‐based tissue engineering approach is being widely used as supporting and guiding cues to promote regeneration of the defects and gaps in the damaged spinal cord . Application of collagen/heparin sulfate after SCI in mice has been reported to improve functional recovery by facilitating Schwann cell (SC) proliferation . Sun et al .…”